The structures and methods disclosed herein relate to optoelectronics and, more particularly, to optoelectronic structures having an optical waveguide that provides a multi-level optical signal pathway and methods of forming such optoelectronic structures.
More specifically, in optoelectronics and, particularly, in optoelectronic integrated circuits, optical waveguides provide on-chip optical signal pathways for transmitting optical signals (i.e., light signals) between on-chip and/or off-chip optical devices including, but not limited to, optical fibers, optical transmitters, optical receivers, and electrical-to-optical or optical-to-electrical transducers. Generally, an optical waveguide includes a core surrounded by cladding. Both the core and the cladding comprise light-transmissive materials (e.g., light-transmissive dielectric materials); however, the core material(s) have a refractive index that is higher than that of the cladding material(s) so that light signals received by the optical waveguide are confined to and propagated along the core. Typically, optical waveguides are formed as single-level structures. That is, they are formed with one or more linear or angled segments on a single level of a chip (e.g., on a single horizontal plane on a chip) and, thereby only allow communication of light signals between optical devices on that same level. Oftentimes, however, it is necessary to communicate light signals between optical devices at different levels (e.g., on different horizontal planes on a chip), but techniques for forming multi-level optical waveguides can be inefficient and costly. Therefore, there is a need in the art for an optoelectronic structure having a multi-level optical waveguide and an efficient and cost-effective method of forming such an optoelectronic structure.